Conservation of energy
The principle of conservation of energy basically states that:
Energy cannot be created or destroyed, it can only be transferred from one form to another.
What that really means is that the total amount of energy in a system is always the same, even if the energy is transferred from one form to another.
Why does it seem like things lose and gain energy?
When we see things losing and gaining energy, it’s because the energy is being transferred from one form to another. For example, when a car slows down, it seems like it’s losing energy, but really the kinetic energy of the car is being transferred to other forms of energy, such as heat energy in the brakes.
A car driving through space
Theoretically, in space, there are no resistive forces such as friction or air resistance, so a car that starts moving will keep moving at that same speed forever - even without accelerating!
Similarly, when braking, we’re adding friction to the system in order to transfer some of the kinetic energy of the car to heat energy in the brakes, which is why the car slows down.
flashcards
| Question | Answer |
|---|---|
| What is the principle of conservation of energy? | Energy cannot be created or destroyed, it can only be transferred from one form to another. |
| What does the conservation of energy mean for the total amount of energy in a system? | The total amount of energy in a system is always the same, even if the energy is transferred from one form to another. |
| When a car slows down, why does it seem like it loses energy? | It seems like it loses energy because the kinetic energy of the car is being transferred to other forms of energy, such as heat energy in the brakes. |
| In space, with no resistive forces, what happens to a car that starts moving? | It will keep moving at that same speed forever, even without accelerating. |
| When braking a car in space, what is being added to the system and why does the car slow down? | Friction is being added to transfer some of the kinetic energy of the car to heat energy in the brakes, which slows the car. |